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Importance of root exudates in plant-soil interactions
Horčičková, Veronika ; Münzbergová, Zuzana (advisor) ; Janoušková, Martina (referee)
Plant roots are in constant contact with soil microorganisms and fungi, and they come in contact with soil fauna and the roots of other plants. All components of the soil biota communicate with each other. When it comes to plants it is often a chemical communication through root exudates, chemicals that plants release into the soil. Through root exudation, plants also affect the abiotic component of the soil, which helps them to obtain nutrients. The production of root exudates is important in attracting symbionts and beneficial organisms and, conversely, in repelling or killing pathogens and parasites. Thanks to root exudates, plants can recognize neighbouring plants, suppress the growth of competitors, or avoid competition with kin, and parasitic plants use root exudates as signals to find its host. By the action of root exudates, plants create their own community of microorganisms and fungi in the rhizosphere, adjust the availability of nutrients and thus actively change living conditions in the soil. This bachelor thesis focuses on plant interactions through root exudates and mentions the ways in which root exudation can be studied. The following diploma thesis will discuss the influence of root exudates of invasive plants on the native plant community.
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Why so specious? The role of pollinators and symbionts in plant population structure and speciation along elevational gradients.
SOUTO VILARÓS, Daniel
This thesis explores the role mutualist pollinators and their symbionts play in the genetic structuring and speciation of their host plants along an elevational gradient in Papua New Guinea. Using the fig and fig-wasp mutualism as a model system, we employed high-throughput sequencing techniques to explore fine-scale population genomics of both fig and wasps along their elevational range. We found there to be clear lowland and highland clustering of tree populations along the gradient, often with a mid-elevation contact zone. In the case of the pollinating wasps, we retrieved the same clustering except in this case, the genetic difference between clusters was high enough as to consider them as separate species. This result supports evidence from other studies challenging the cospeciation paradigm of one wasp species per fig species. In addition, we explore ecological traits which may promote, or at least, maintain, reproductive isolation between fig (sub)species along with behavioural preference tests from pollinating wasps. In order to further investigate the mechanisms promoting wasp speciation along the gradient, we describe Wolbachia infection status as well as strain type. Wolbachia-induced cytoplasmic incompatibility (CI) is often invoked as a possible speciation agent since it can rapidly provoke and maintain reproductive isolation between otherwise freely interbreeding insect populations. Finally, we explore non-pollinating fig wasp (NPFW) diversity along the gradient for a subset of our focal species. Our study reveals that there is a tight relationship between NPFW diversity and host species, and a mid-elevation peak.
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Mechanisms affecting plant-soil feedback in invasive species
Drtinová, Lucie ; Münzbergová, Zuzana (advisor) ; Rumlerová, Zuzana (referee)
Invasive plants worldwide cause considerable ecologic and economic damage. In order to prevent this, it is necessary to understand the mechanisms of plant invasion. One of the explanations of the success of invasive plants is their effective use of feedback interactions between plant and soil. Plant-soil feedback greatly affects the prosperity of a plant. While in most plants the intraspecific feedback is negative, invasive species show less negative or even positive intraspecific feedback. This may be due to the fact that invasive plants have the ability to alter soil composition to their advantage. This work deals with the individual components of plant-soil feedback, abiotic and biotic factors influencing the process, and summarizes their importance for plant invasion. The subject of the following diploma thesis will be a research on the significance of the individual biotic and abiotic components of the plant-soil feedback and assessing their importance for plant invasion. Key words: plant invasions, plant-soil feedback, mutualism, biotic factors, abiotic factors
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